Recently I let my 1055T go down to stock speeds from 3.5GHz. What a difference! When all cores are working, the temperatures used to be around the low 60s... now it's 46-47C! I didn't even touch the voltages. Have you folks noticed the same huge variation in working temperature just from a 700MHz overclock?

Since I'm now running BOINC, I'm going to keep it at the slower speeds, because the difference in temperature is just too great, and it's warmer nowadays too.

13C difference seems a bit high to me if you left the voltage at stock values? Did you manually set voltage to the stock ~1.35V or are you allowing the mobo to apply "auto" voltage in which it will typically automatically apply extra voltage if you overclock. Might want to overclock it back up to 3.5GHz and check CPUz running Prime95 or Intel Burn Test to see what the voltage is reading under load. At stock voltage, temps shouldnt raise too much. But when you start pumping more voltage into the CPU, you could see a 10C jump. Here is a 1055T overclock at stock voltage

Also, what type of cooler are you using? 6 fully loaded and overclocked 125W TDP cores is a lot for a stock heatsink to cool. You might have exceeded the cooling capacity of your CPU cooler in your overclock, causing temps to go high.

I figured it out! I had left CPU load line calibration on "auto", and thus when it was under load the mainboard (M5A99X EVO) automatically cranked up the VCore to around 1.5V. That was what had caused the incredible temperature jump! Now that I've switched it to "regular", which means no load line calibration, the voltage stays at stock.

Now the temperatures under load are 53C, which is a reasonable increase from 43-46C before the overclock. I'm leaving LLC to off, I don't like it automatically increasing the voltage without my knowledge.

In theory, power dissipation of a CPU should scale roughly linearly with frequency, and with the square of the VCore. Furthermore, the temperature delta above ambient should be proportional to the power dissipated (yes, I'm assuming the fan speeds don't change... details, details).

Assuming an ambient of around 23C, all of these numbers make sense now (plus or minus a few degrees). It is nice when theory and practice agree!

Oh, and from what I've seen, low 60s was probably nothing to worry about; AMD's CPUs are tough little beasties! (My Phenom 9550 ran for an unknown number of days at 100C after the CPU fan died, and suffered no apparent ill effects... it still runs my web server to this day. Though I do wonder why there wasn't an automatic thermal shutdown.) But no sense consuming excess power and generating extra heat needlessly; glad you got it sorted!

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

I agree with Forge. LLC is meant to prevent voltage drop when the CPU gets loaded up. My understanding is that: normally LLC shouldnt increase voltage, just keep it from dropping. Increasing voltage is nornally left to an "Auto" VCore voltage setting. But hey, if adjusting LLC fixed the problem, I can't really argue that.

Well when I enabled LLC on my other board (M4A88TD-V EVO/USB3), it always overcompensated and ended up giving more voltage to the CPU when it was under load than when it was idle. Specifically, around 1.488V when idle, 1.525V loaded.

The M5A99X EVO provides an option to adjust the compensation, but I had left it on "auto", so it's understandable that it ended up overcompensating again too.

It's reassuring that it can withstand high temperatures, but still I wouldn't like the temps to go that high, otherwise the fans kick into overdrive and the computer ends up heating my small dorm room which is the last thing I need now that winter's over. Besides, I always feel like "it can do better" when I look at the temperatures.

It sounds like LLC is a kludge to avoid having to implement a feedback mechanism (from the power pins at the CPU socket) to control the VCore regulator on the motherboard. IOW they're guesstimating how much the voltage will droop due to electrical resistance of the power plane and CPU socket, and boosting the output by a corresponding amount. They're trying to fix something in the BIOS firmware which really ought to be handled by a physical change to the design of the PCB and VRMs...

Re LLC overcompensating... it probably isn't, or at least isn't overcompensating as much as you think. Unless the sensor you're getting that readout from is on the CPU it will be measuring the boosted voltage, which will be lower by the time it goes through the resistance of the power plane and the CPU socket contacts.

When you're dealing with low voltages and currents approaching 100 amps, resistance of the power plane and the socket becomes very significant!

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

From my limited experience with multiple Asus mobos, I've noticed LLC over-boosting voltage more with AMD Phenoms than with Intel C2Q's when overclocking. In higher-end motherboards, you get to select the amount of LLC, in some you get settings (off, low, medium, high, extreme) and in low-end boards LLC is on/off.

I'm guessing the reason for LLC is to ease the burden on the VRMs during heavy overclocking, without having to burden the user with the granularity of setting voltage levels for each CPU power state.

Yeats wrote:I'm guessing the reason for LLC is to ease the burden on the VRMs during heavy overclocking, without having to burden the user with the granularity of setting voltage levels for each CPU power state.

It isn't going to "ease the burden" on the VRMs. If anything it will increase it, since they're being asked to pump out more power than they would without LLC.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

just brew it! wrote:It sounds like LLC is a kludge to avoid having to implement a feedback mechanism (from the power pins at the CPU socket) to control the VCore regulator on the motherboard. IOW they're guesstimating how much the voltage will droop due to electrical resistance of the power plane and CPU socket, and boosting the output by a corresponding amount. They're trying to fix something in the BIOS firmware which really ought to be handled by a physical change to the design of the PCB and VRMs...

Yeah, and isn't "digital" VRM supposed to deliver smoother power delivery anyway? IMO that should almost negate the need for LLC altogether. Sounds like ASUS (and probably others) are using LLC nowadays for things it wasn't originally designed for.

Yeats wrote:I'm guessing the reason for LLC is to ease the burden on the VRMs during heavy overclocking, without having to burden the user with the granularity of setting voltage levels for each CPU power state.

It isn't going to "ease the burden" on the VRMs. If anything it will increase it, since they're being asked to pump out more power than they would without LLC.

Sorry, I should have said "ease the burden" on the reaction times for the VRMs. The circuitry isn't as responsive as the CPU.

just brew it! wrote:It sounds like LLC is a kludge to avoid having to implement a feedback mechanism (from the power pins at the CPU socket) to control the VCore regulator on the motherboard. IOW they're guesstimating how much the voltage will droop due to electrical resistance of the power plane and CPU socket, and boosting the output by a corresponding amount. They're trying to fix something in the BIOS firmware which really ought to be handled by a physical change to the design of the PCB and VRMs...

Yeah, and isn't "digital" VRM supposed to deliver smoother power delivery anyway? IMO that should almost negate the need for LLC altogether. Sounds like ASUS (and probably others) are using LLC nowadays for things it wasn't originally designed for.

just brew it! wrote:voltage will droop due to electrical resistance of the power plane and CPU socket

It would be a big step for the computer industry to finally learn how to use superconductivity for the purpose of preventing any and all unwanted voltage drops in CPU sockets. So much money has been invested into such research, does anybody know any positive outcome?

Crayon Shin Chan wrote:I figured it out! I had left CPU load line calibration on "auto", and thus when it was under load the mainboard (M5A99X EVO) automatically cranked up the VCore to around 1.5V. That was what had caused the incredible temperature jump! Now that I've switched it to "regular", which means no load line calibration, the voltage stays at stock.

Yep, I've found that the "AUTO" voltage settings seem to always use way more voltage than is needed. I've even seen cases where it uses so much voltage that the overclock becomes unstable, and manually setting it lower makes it completely stable.

just brew it! wrote:voltage will droop due to electrical resistance of the power plane and CPU socket

It would be a big step for the computer industry to finally learn how to use superconductivity for the purpose of preventing any and all unwanted voltage drops in CPU sockets. So much money has been invested into such research, does anybody know any positive outcome?

Not for consumer products. Even "high temperature" superconductors still require some pretty extreme cooling (-262 degrees F), making them completely impractical for everyday use.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

just brew it! wrote:It sounds like LLC is a kludge to avoid having to implement a feedback mechanism (from the power pins at the CPU socket) to control the VCore regulator on the motherboard. IOW they're guesstimating how much the voltage will droop due to electrical resistance of the power plane and CPU socket, and boosting the output by a corresponding amount. They're trying to fix something in the BIOS firmware which really ought to be handled by a physical change to the design of the PCB and VRMs...

Re LLC overcompensating... it probably isn't, or at least isn't overcompensating as much as you think. Unless the sensor you're getting that readout from is on the CPU it will be measuring the boosted voltage, which will be lower by the time it goes through the resistance of the power plane and the CPU socket contacts.

When you're dealing with low voltages and currents approaching 100 amps, resistance of the power plane and the socket becomes very significant!

Some time ago I read an Intel paper on LLC, apparently it was introduced with the Core 2 processors. The thing is, when you draw a lot of current (i.e. when the CPU is loaded), the voltage in any circuit naturally drops. If the drop (called Vdroop) is big enough, the voltage may not be enough for the CPU to be stable. LLC exists to bring the voltage back up and should be on all the time, according to Intel. A large part of the paper discussed the time delay between the CPU suddenly drawing a lot of current and the LLC bringing the voltage back up to compensate, during which the CPU might be unstable. This explains the "CPU Voltage Frequency" option within the M5A99X EVO's UEFI, which controls the "VRM transient response" to these kinds of sudden change behaviours. The higher transient response, the less time the CPU will receive a reduced voltage when it goes from 0-100% usage while waiting for the LLC to kick in.

I don't think the resistance of the power plane and the CPU socket contacts is important. It never changes anyway because the temperature of the board shouldn't change that much.

Holy thread necro, Batman! (Might have originally been a spam necro, with the spam post since nuked...)

I think you misunderstood the post you were responding to. Of course the voltage will tend to drop when you draw more current. That's why I am questioning why VRMs don't implement some form of remote sensing, i.e. direct feedback from the CPU's power bus to the VRM. Seems to me this would eliminate the need for LLC (unless I am misunderstanding things, and remote sensing would not solve the problem that LLC deals with).

ATX PSUs have implemented remote sensing for years on the 3.3V rail, with a separate sense wire coming back from one of the 3.3V pins to the PSU. This wire carries no current; its purpose is to allow the PSU to sense the voltage at the motherboard end of the wiring harness, after the voltage drop due to the wire resistance.

Also, I never said the resistance of the motherboard's power planes or socket contacts was changing. The amount of current flowing changes, which causes the voltage drop across the (constant) resistance to vary, according to Ohm's Law.

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson